Question 28

cal value for the confidence level you want. Use [a = 0.5 if you don't have a good idea about the value of f). 8.2 TECHNOLOGY CORNER TlNspire Instructions in Appendix B; HP Prime instructions on the book's Web site. 15. Confidence interval for a population proportion Section 8.2 EXBrClSBS For Exercises 27 to 30, check whether each of the condi- at his college. Thirtyeight of those interviewed think tions is met for calculating a confidence interval for the tuition is too high. populatm\" \"mom\" P' 29. AIDS and risk factors In the National AIDS Be- 27. Rating school food Latoya wants to estimate what havioral Surveys sample of 2673 adult heterosexuals, pg. proportion of the seniors at her boarding high school 0.2% had both received a blood transfusion and had 9 like the cafeteria food. She interviews an SRS of 50 a sexual partner from a group at high risk of AIDS. of the 175 seniors living in the dormitory. She nds We want to estimate the proportion p in the popula- that 14 think the cafeteria food is good. tion who share these two risk factors. 28. High tuition costs Glenn wonders what proportion 30. Whelks and mussels The small round holes you of the students at his school believe that tuition is too often see in sea shells were drilled by other sea high. He interviews an SRS of 50 of the 2400 students creatures, who ate the former dwellers of the shells